The purpose of this circuit found in an old Elektor is to light a lower power lamp when the bigger one burns out. The loads depend on the triacs.
This amplifier for public address was found in English documentation from 1967. The transistors are from...
January 2017 - Pulse Electronics ER11 transformers with high insulation can be obtained from...
With only 1% distortion, this Motorola amplifier found in a 1968 documentation makes use of period...